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    ArrayIterator::uasort

    (PHP 5 >= 5.2.0, PHP 7, PHP 8)

    ArrayIterator::uasort — Sort with a user-defined comparison function and maintain index association

    Description

    public ArrayIterator::uasort(callable $callback): true

    This method sorts the elements such that indices maintain their correlation with the values they are associated with, using a user-defined comparison function.

    Note:

    If two members compare as equal, they retain their original order. Prior to PHP 8.0.0, their relative order in the sorted array was undefined.

    Parameters

    callback

    The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.

    callback(mixed $a, mixed $b): int
    Caution

    Returning non-integer values from the comparison function, such as float, will result in an internal cast to int of the callback's return value. So values such as 0.99 and 0.1 will both be cast to an integer value of 0, which will compare such values as equal.

    Return Values

    Always returns true.

    Changelog

    Version Description
    8.2.0 The return type is true now; previously, it was bool.

    See Also

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    User Contributed Notes 1 note

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    1
    Massimiliano Arione
    9 years ago
    Even if documentation says that $cmp_function must be a string, this method works with a Callable also.
    Example:

    <?php

    $iterator    ->uasort([$this, 'usort']);  // 'usort' here is a method in the same class
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